Cross-Seasonal Influence of the SAM on Southern Hemisphere Extratropical SST and its Relationship with Meridional Circulation in CMIP5 models

Using outputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5) models, the influence of the December-February (DJF) Southern Hemisphere Annular Mode (SAM) on March-May (MAM) zonal-mean meridional circulation found in reanalysis data is assessed. Considering that the DJF Southern Hemisphere extratropical SST pattern associated with the SAM (SESST hereafter) acts as an important bridge' in the cross-seasonal influence of the DJF SAM on MAM meridional circulation, model performance in simulating the influence of the DJF SAM on SESST and in capturing the connection between SESST and MAM meridional circulation are investigated. Most of the models are equipped to capture the influence of the DJF SAM on SESST. However, the model-simulated influence is stronger than the observations, which is partially attributed to an overestimation of the association between the SAM and surface zonal wind by these models. The simulated cross-seasonal influence of the DJF SAM on MAM meridional circulation tends to be closer to the observations in models with high performance in depicting the influence of MAM SESST on MAM meridional circulation than in models with relatively low performance.